1. Field of the Invention
The present invention relates to a device for adjusting the relative position of two parts of the same piece, by deforming an intermediate zone connecting these two parts together, by means of a conical screw.
It relates more particularly, but not exclusively, to such an adjustment on pieces obtained by stamping and, possibly, deformation of a sheet material such as a metal strip.
It applies more particularly to the mounting of bimetal strips used in thermal tripping apparatus such for example as thermal relays.
It is known in fact that in this type of application the tripping threshold of such apparatus depends, among other things, on the relative position of the bimetal strips and on the tripping members which are associated therewith.
Considering the manufacturing tolerances, it has proved impossible to obtain during assembly sufficient accuracy so as to obtain in the same series of apparatus strictly identical tripping thresholds. This is why it is then necessary, at the end of assembly, to adjust the position of the bimetal strips. Now, in the present state of the technique, this adjustment is a delicate operation, often carried out manually by specialized staff. It is then time wasting and does not lend itself to high rates of production of such apparatus.
2. Description of the Prior Art
To try to overcome these drawbacks, attempts have already been made to mount the bimetal strips on metal sheet pieces having a support area which may be mounted on a fixed part of the apparatus, for example the case, and a fixing area on which the bimetal strip is mounted, this fixing area extending normally to the support area, the connection of the support area to the fixing area then being formed by a deformable zone including a tapped bore and an open cut out at the level of a first edge of the piece and extending as far as said bore.
The adjustment was then provided by screwing a conical screw into the tapped bore so as to generate, by a torque effect, a torsion of the deformable zone included between the bore and a second edge of the piece opposite said first edge and so as to cause accordingly rotation of the fixing zone. In order to reduce the screwing torque required for causing said torsion, it has also been proposed to reduce the width of the deformable zone by providing a second cut out in the second edge, opposite the first edge.
However, this solution also has a number of drawbacks.
In fact, despite the presence of the second cut out, the torque required for screwing in the conical screw remains high and metal stripping has further been observed due to the fact that the force exerted by the conical screw is only applied to a very small number of threads of the bore and, because of the deformation, only to a very small part of their circumference.
Another drawback of this solution resides in the fact that, for reasons which will be discussed hereafter, the deformations to which the deformable zone is subjected subsequent to screwing, do not allow the inherent flatness of this zone to be maintained and on the contrary cause buckling thereof. Consequently, instead of having a rotational movement of the fixing zone about an axis perpendicular to the support zone, a skew movement will be obtained, incompatible with the desired adjustment function.
The purpose of the invention is then more particularly to overcome these drawbacks.